A conventional load detection apparatus for an elevator described in Japanese Patent Application Laid-Open No. 7-101646 is shown in FIG. 9. In this figure, 1 designates main ropes (or ropes), 2 shackles, 3 detection boards, 4 studs, 5 wires, 6 pulleys, and 7 differential transformers.
This load detection apparatus for an elevator is installed in a machine room arranged on the top of a vertical passage for an elevator car. When the plurality of shackles 2, with which end portions of the main ropes 1 for hanging the elevator car are connected, are caused to move under the action of the load of the car, the detection boards 3 are displaced in accordance with the movements of the shackles 2 while being guided by the studs 4, whereby the loading capacity of the car is detected based on the displaced positions of the detection boards.
The displacement of each detection board 3 is once converted into a rotary motion by means of a corresponding pulley 6 through a corresponding wire 5, which is again converted into a linear motion with its direction being changed, whereby a corresponding differential transformer 7 is operated to detect the load. Each differential transformer 7 converts the displacement of a corresponding detection board 3 transmitted through a corresponding wire 5 into an electric signal.
With the conventional apparatus as constructed above, since a space for installation of each differential transformer is required and each differential transformer acting as a sensor has sliding portions, the detection operation is not stabilized for a long period of time, and it is necessary to frequently conduct tests or inspections.